Sheet for extraction, extraction filter, and extraction bag

Abstract

An extraction sheet having high machinability in the manufacture of an extraction filter for beverages and an extraction filter using the same and having high handling property is provided. The extraction sheet includes a layer including a meltblown nonwoven fabric that is formed from fibers of a polylactic acid-based resin having a crystallinity of 9.0% or lower and a fiber diameter of 15.0 μm or smaller and that has a basis weight of 2.0 to 30.0 g / m2, and a layer including a spunbonded nonwoven fabric that is formed from fibers of a polylactic acid-based resin having a crystallinity of 30.0 to 60.0% and a fiber diameter of 35.0 μm or smaller and that has a basis weight of 5.0 to 30.0 g / m2. The extraction sheet has a bending hysteresis of 5.0×10−3 to 14.5×10−3 gf·cm / cm.

Description

TECHNICAL FIELD[0001]The present invention relates to an extraction sheet for extracting beverages or the like from an extraction material such as tea leaves and powder coffee, and to an extraction filter and an extraction bag formed by, for example, cutting or welding the extraction sheet (hereinafter the extraction filter and the extraction bag together may be referred to as “extraction filters”), and in particular, relates to an extraction sheet having high machinability in the manufacture of the extraction filters, and to extraction filters that are formed with the extraction sheet and have high handling property.BACKGROUND ART[0002]Conventionally, the extraction sheets used as the material of filters or bags for extracting beverages such as black tea, green tea, and coffee, liquid food such as soup stock, drugs such as Kampo products, or quasi drugs such as bath salts are made from a nonwoven or a woven fabric made of resin, or paper in order to increase the rate of extraction ...

AI Technical Summary

Benefits of technology

[0018]Since the extraction sheet according to the first aspect of the present invention includes the layer M formed from the meltblown nonwoven fabric that is formed from fibers of the polylactic acid-based resin having a crystallinity of 9.0% or lower and a fiber diameter of 15.0 μm or smaller and that has a basis weight of 2.0 to 30.0 g / m2, and has a bending hysteresis of 5.0 gf·cm / cm or larger, the extraction sheet has a characteristic of being creasable.

[0019]Therefore, in the manufacture of the extraction filters with such an extraction sheet, the guide members, for example, are placed on the manufacturing line and the extraction sheet is folded in half or otherwise bent to form the crease line along the conveyance direction of the manufacturing line, enabling the extraction sheet to be in a tight and straight condition. Consequently, the extraction sheet can be prevented from meandering upon being conveyed, for example, improve its machinability, and be prevented from causing defective products.

[0020]In addition, such an extraction sheet is creasable but nevertheless hardly in what is called the “wrinkled” condition where many unwanted crease lines or wrinkles are formed, because the extraction sheet has a bending hysteresis of 14.5×10−3 gf·cm / cm or smaller. Thus, the extraction sheet hardly impairs its good appearance.

[0021]The term “bending hysteresis” as used herein refers to an index that shows the recovering ability of the extraction sheet upon unloading after the sheet is bent by loading. The higher the index value, the more hardly the extraction sheet will recover and the more creasable the extraction sheet will be.

[0022]In addition, in the manufacture of such an extraction sheet into an extraction bag in the form of a pillow filled with an extraction material, the crease line can be appropriately formed to provide the extraction bag having improved shape retention. Thus, the extraction bags, even when stacked, can be steady and hardly slip down. Hence, a method of packaging can be employed such that the extraction bags in stack are conveyed as a whole, and are housed as a whole in one external container. Therefore, the extraction bags have high handling property and can enhance the manufacturing efficiency.

[0023]Furthermore, since the above-described extraction sheet comprises the layer S including the spunbonded nonwoven fabric that is formed from fibers of the polylactic acid-based resin having a crystallinity of 30.0 to 60.0% and a fiber diameter of 35.0 μm or smaller and that has a basis weight of 5.0 to 30.0 g / m2, the extraction sheet has a high tensile strength and is firm.

Problems solved by technology

However, since an extraction sheet comprising a nonwoven fabric with small basis weight is generally thin and flexible, the extraction sheet is difficult to handle upon being processed into extraction filters, and thus has a problem of low machinability.

This forms inclined cutting or sealing lines, causing defective products.

In addition, since an extraction bag in the form of a pillow filled with an extraction material such as tea leaves generally swells non-uniformly with the extraction material, the extraction bags, when stacked, tends to become unsteady.

In particular, since an extraction bag comprising a conventional nonwoven fabric is flexible, is easily deformed, and has a smooth surface, the stacked extraction bags are unsteady, so that the stacked extraction bags easily slip down from the upper part of the stack.

Hence, it is difficult to convey the extraction bags in stack or house them in an external container, which causes a problem of poor handling property.

Although, the filter for food described in Patent Literature 1 includes the layer of the meltblown nonwoven fabric comprising the fibers of the polylactic acid-based resin, the filter for food is nevertheless hardly creasable due to the high crystallinity of the resin forming the meltblown nonwoven fabric layer.

Hence, this filter for food has a problem of failing to enhance machinability by forming the crease line.

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